Recently, various complexes of radionuclides have been proposed for the external imaging of various portions of the anatomy. Various compositions have been found to localize to a greater extent in certain organs than in others thereby enabling the imaging of that organ, utilizing a suitable radioactivity sensitive camera, etc.
Of the agents currently employed for skeletal imaging, the radionuclides Strontium 85 and Fluorine 18 have found widespread use. Fairly recently, complexes of Technetium-99m with various organic complexing agents have been found to be superior to the strontium 85 and fluorine 18 agents. Generally, the complexing agents employed are organic phosphate and phosphonate chelating agents. See Perez et al, J. Nucl. Med. 13:788-789, 1972; Subramanian et al, Radiology, 98: 192-196, 1971; Subramanian et al, Radiology, 102:701-704, 1972; Subramanian et al, J. Nucl. Med., 13:947-950, 1972; Tofe et al, J. Nucl. Med., 15:69-74, 1974; Yano, J. Nucl. Med., 14:73-78, 1973; Castronova et al, J. Nucl. Med., 13:823-827, 1972; and Subramanian et al, J. Nucl. Med., August, 1975 (U.S. application Ser. No. 368,473, filed June 11, 1973).
It was found that when solutions of these Technetium-99m phosphate and phosphonate complexes are given intravenously, the Technetium-99m localizes to a great extent in bone, particularly in diseased or abnormal areas of the skeleton. Good visualization of both normal bone and skeleton lesions is observed about 2 hours after administration of the complexes. Normal and abnormal skeletal tissues are readily delineated using conventional radioisotope imaging devices such as rectilinear scanners or scintillation cameras.
There has been a continuing search in this area for other radionuclides and complexing agents with high bone uptakes suitable for skeletal imaging where Technetium 99m and/or the complexing agents utilized heretofore are not available.